This invention is particularly appropriate for embodiment in freight car identification system. Every freight train contains cars from many different railroads, and the respective cars may have many different destinations. An identification (I.D.) code that can be fed into a central computer facilitates the loading, unloading, accounting for, and supervising the movement of all of the freight cars in a yard or on the trackage of a system.
In order to keep track of railroad cars, freight car I.D. systems have been devised, and are in use. These existing I.D. systems use optical scanners (which identify color coded identification plates on passing freight cars.) However, these optical I.D. systems have a serious deficiency; the optical scanners become disrupted when the coded identification plates become coated with dirt or when fog, snow or rain interrupt the optical scanning path.
A microwave freight car I.D. system embodying the present invention has the advantage that it is oblivious to dirt, fog, snow and rain. This microwave I.D. system has the following additional advantages over the prior optical scan system:
(1) It is self-checking, in that indication of a freight car passing (with an identification unit) occurs independently of the transmission of a digital identification code.
(2) The train does not have to slow down for accurate identification.
(3) The distance from the train to the identification interrogation equipment is not critical.
(4) The speed of the train can be checked, as a by-product.
(5) The I.D. word generator in the panel can be programmable to provide routing and delivery information, data on vehicle contents, weight, etc.